Feline infectious peritonitis (FIP), a fatal disease in cats worldwide, is caused by FCoV infection, which commonly occurs in multicat environments. The enteric FCoV, referred to as feline enteric virus (FECV), is considered a mostly benign biotype infecting the gut, whereas the FIP virus biotype is considered the highly pathogenic etiologic agent for FIP. Current laboratory tests are unable to distinguish between virus biotypes of FCoV. FECV is highly contagious and easily spreads in multicat environments; therefore, the challenges to animal shelters are tremendous. This review summarizes interdisciplinary current knowledge in regard to virology, immunology, pathology, diagnostics, and treatment options in the context of multicat environments.